can somone provide a link to load's of info about rx's, tx's and compatibility.

i plan on buying a sport arf and need rx and servos to go along with my jr quatro tx for the alpha 40 and i'm not looking to spend a bunch of money to upgrade tx.

what is your advice.

here are some of the info i'd like to know:

1, if i buy rx and servo's for a second plane to go along with the jr quattro for now, what componets will be compatible with an upgraded computer tx.
2, difference between fm and pcm, are they compatible?
3, can i run futuba rx with a jr tx?
4, digital servo's are they compatible with fm rx?

No links handy but can try to provide a few quick answers.
1. The JR Quatro is a FM transmitter so you need a RX that is compatible with their "positive shift" modulation system. These days virtually ANY servo will work with ANY RX. You MAY need to trim off a polarity key on the outside of the plug like on Futaba servos or you may need to change the wiring in the plug very slightly, easy to do. RCKen has a nice diagram of this I'm betting he will kick in here with soon.
2. Most PCM transmitters can be made to transmit FM also. PCM is actually a form of FM. Each mfg has their own PCM code and they are NOT interchangeable. This does not effect the servos in any way. The TX MUST be able to XMIT in the same modulation format as the RX.
3. NO, unless JR has come up with a TX that can switch to "negative shift" transmissions. It would likely be in one of their expensive sets.
4. The servos don't care what they are plugged into as long as the wiring code matches. They work fine with AM, FM, PCM and Ouija boards. Well, OK maybe not the last. Digital or analog, all work fine. Digital usually use more power depending on torque available.

Edited to correct shift types. oops.

JR Transmitters work on positive shift, as do Airtronics transmitters. Futaba and HiTec transmitters work on negative shift. HiTec and Airtronics make a couple of models of transmitter that are shift selectable (Eclipse 7, RD6000 Super), so they can use either positive or negative shift receivers.

JR, HiTec, and Cirrus make shift selectable receivers that can be used with either type of transmitter, positive or negative shift. Receivers from Futaba, including ones branded as Hobbico or Tower Hobbies receivers, only use negative shift and cannot be used with a positive shift transmitter.

JR Sport and HiTec both offer flight packs including shift selectable receiver, receiver battery, 4 servos, and power switch for $99.99 plus the cost of a receiver crystal. Airtronics offers a standard flight pack with positive shift receiver, receiver battery, 4 servos, power switch and servo extension all for $119.99. Hobby People is currently offering the Cirrus RX-8 shift-selectable receiver for $29.99 plus $9.99 for the crystal. You can match the Cirrus RX-8 dual conversion receiver to the servos, power switch, and receiver battery of your choice to create your own flight pack.

Happy shopping

Bruce,
here ya go. here's the servo diagram.

Ken

Whoa, i'm sure glad i asked and i'm more glad ya'll generously responded thanks alot, very helpful.

i'm also looking at used equipment that's why i asked these questions. i did know about the flight packs, and i did download the diagram when i first got started in this hobby(just recently) thanks rcken, i figured it would come in handy some day.

that cirrus looks like a pretty good deal!

thanks again!!!!!!!!

I just fixed my previous post where I had the shifts wrong. Oops. [sm=spinnyeyes.gif]

Check out this link. MIght be more info thanyou wanted, and might not even answer your question but it's a good read. From a sailplane site, so he refrences a lot of sailplane stuff the the princples are the same....

[link]http://www.torreypinesgulls.org/radios.htm[/link]


Andy